ISHS Acta Horticulturae 278: Symposium on Scheduling of Irrigation for Vegetable Crops under Field Condition
THE INFLUENCE OF DIFFERENT IRRIGATION SCHEDULING METHODS ON THE LEAF AREA INDEX, LEAF AREA DURATION AND BULB FORMATION OF LONG-SEASON ONIONS |
| Authors: | J.J. Human, P.J.L. Grobler |
| Abstract:
To determine the influence of irrigation scheduling methods and spacing (population) on the growth and production of long-season onions, an experiment was conducted in the field on plots equipped with floating lysimeters. Irrigation scheduling methods were based on crop growth period, soil matrix potential, tensiometers, visual (measured) symptoms, class A pan evaporation and a crop growth mathematical simulation model (PUTU). Two spacings were used: a low population (5 cm x 30 cm) and a high population (5 cm x 15 cm). Irrigation scheduling methods had different influence on the LAI at 15 weeks after transplanting when bulb formation commenced. The irrigation scheduling methods had different effects on the LAD for the period from transplanting until 15 weeks after and till maximum LAI was reached. The LAI at 13 and 15 weeks after transplanting and the LAD for the period of 13 to 17 weeks (maximum LAI) after transplanting correlated significantly with the final dry mass yield of the onions. Irrigation scheduling methods (and possibly drought stress) influenced LAI, LAD, the bulb formation period, and yield. | |
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